On why MLRS used for anti shipping is a bad bad idea.
I can't shake the feeling that I was watching a colorized WWII footage about an aerial bombing against a moving ship.
It reveals more about the Russian's lack of precision strike capability even if they managed to destroy the ship.
Well "happy" or "satisfied" I will leave that up to you
There are - see Ukraine issue - around 130-150 Marder available at KMW/Rheinmetall Landsysteme, even including IIRC around 60 A1A4 and A1A5
Due to the TAM tanks development, there are several deep fording kit's available
In short, I believe the Indonesian Army is quite satisfied with the Marder. While Rheinmetall might have a chance in offering those deep fording kits, but I personally think that it may be better if the company offers a more thorough upgrade package for the Marder suited with Indonesia's needs and financial condition.
Also, perhaps the company can offer something like a joint project between FNSS and Pindad for Harimau tank. But in this case, a lighter one and with amphibious capability in similar function like the PT-76s for the Indonesian Marine Corps.
Imagine a better protected and better performing amphibous light tank with 105 mm high-pressure cannon that is also able to launch ATGM as well.
Anyway, these are just my wild ideas. Something that just crossed my mind just now.